The invention relates to a planar circuit for a millimeter-wave continuous wave (CW) transceiver especially for use in radar.
With pulsed radars, the transmitter sends out periodic pulses and during the interpulse period the transmitter is switched-off and a receiver is switched-on to receive energy reflected by objects in the path of the transmitted beam. In the case of continuous wave radar there is simultaneous transmission and reception of energy by way of one and the same antenna. In order to separate the signals a magnetic circulator is provided having an input port connected to an RF source, a output/input port coupled to an antenna and an output port for the received signal. The received signal is applied to a mixer in which it is mixed with a local oscillator signal derived by coupling-out a portion of the signal from the RF source. A disadvantage of this known arrangement is that the circuit, particularly the magnetic circulator, cannot be fabricated in monolithic technology.